class Person:
    nums = 0
    def __init__(self,name,age,city):
        self.name = name
        self.age = age
        self.city = city
        Person.nums += 1
    # 实例的方法
    def show(self):
        print(self.name)
        return self.city
    # 类方法
    @classmethod
    def show_nums(cls):
        print(cls.nums)
    # 静态方法
    @staticmethod
    def show_age(age):
        print("年龄是：",age)
p1 = Person("zhangsan",20,"shanghai")
p2 = Person("lisi",21,"beijing")
print(p1.show())
print(p2.show())
Person.show_nums()
Person.show_age(20)